This invention relates to a color television camera system and more particularly to contour enhancement in a color television camera which has the effect of subjectively increasing the picture sharpness.
Present day broadcast color television cameras use some form of "aperture correction" or "contour correction" to have the effect of increasing the picture sharpness. This correction, often referred to as "contour correction" corrects for the apparent loss of resolution in the system due to, for example, the horizontal and vertical high frequency response of the image pickup devices and display devices. In cameras using red, green and blue camera pickup devices, the high frequency horizontal and vertical spatial information from the green signal is extracted and after amplification, this high frequency spatial information is added back to each of the three color signals or directly to the luminance signal. The use of the green signal only is to prevent misregistration enhancement. The problem with this system is that scenes containing little or no green information appear soft or lacking in sharpness (lacking in detail).
Although systems which sense the red, green and blue camera signals having the largest amplitude and using that signal to provide the aperture or contour correction are known, this type of system would produce false edge information when there was minor misregistration. In fact, such a system would produce enhancement of this misregistered signal.